Process for the preparation of highgrade antiknock motor fuels



.knock gasoline polymerizates.

Patented July 9, 1946 PROCESS FOR THE PREPARATION OF HIGH- GRADE ANTIKNOCK MOTOR FUELS August Hagemann,

Duisburg-Meiderich, Germany; vested in the Alien Property Custodian No Drawing. Application March 10, 1941, Serial No. 382,639. In Germany February 8, 1940 6 Claims. 1

Unsaturated low molecular hydrocarbons, such as are obtained for example in the catalytic cracking of high molecular hydrocarbons, can be converted by prior art methods into highly anti- However, in hydrogenating these polymerizates, which is absolutely necessary for producing motor fuels suitable for aircraft purposes, the anti-knock property of the gasolin is greatly decreased.

The object of the present invention is to convert these hydrocarbons, especially those with from 3 to 5 carbon atoms, into a product which, even after hydrogenation, has excellent antiknock properties. To obtain this result, the low molecular hydrocarbons are treated with carbon monoxide and hydrogen at high pressures of about 50-200 atmospheres, and temperatures of up to, and if necessary above, 300 C. (572 F.). Alcohol are thus formed, which are converted at normal pressure into alkenes having branched chains, by the usual process of heating with dehydrating means, such as alumina. Subsequently, a hydrogenation is conducted. If desired, the treatment with carbon monoxide and hydrogen may be repeatedly carried out with the alkenes obtained, until the hydrogenated final products have the boiling points required for application as aircraft gasoline.

Before the watergas treatment it is advisable to introduce a selective polymerization step, whereby only the iso-hydrocarbons are polymerized. Then, by the addition of a methyl group through the watergas treatment, the polymerizates obtained yield compounds which, as regards their anti-knock property, even surpass isooctane.

Furthermore, before the watergas treatment, it is advisable to treat the starting material with borylphosphate, fullers earth or similar substances at a high temperature, for example at 200-300 C. (392-5'72 F.), partly in order to isomerize the unsaturated hydrocarbons, and partly to shift the double bond towards the middle of the molecule, which is very favourable for the addition of branched-chain methyl groups through the watergas treatment. In the same Way, the final hydrogenation can be preceded by another treatment with agencies such as borylphosphate, fullers earth, etc.

A very favourable mode of execution of the above described process results if the products obtained after the dehydrating step are separated into three fractions, a low-molecular fraction, a high-molecular fraction within the gasoline boiling range, and a medium-molecular fraction. The low molecular hydrocarbons are then recycled and subjected to the treatment with isomerizing means'which precedes the watergas treatment, while the medium molecular hydrocarbons are recycled to the watergas treatment used for the preparation of alcohols, if desired after the treatment with borylphosphate, etc. On the other hand, the higher molecular fractions, if desired after further treatment with borylphosphate etc., are immediately subjected to hydrogenation. In this way, for example, it is possible to effect a thoroughly satisfactory conversion of the C3- to cs-hydrocarbons, obtained in large quantities by the catalytic cracking, into Valuable aircraft gasoline.

If desired, one can add to the aircraft gasoline the saturated Cs-hydrocarbons, which during the Watergas treatment pass off with the saturated Csand C i-hydrocarbons that escape as gases, while the latter may be used as fuel gas.

The process described permits a practically complete conversion of the C3- to cs-hydrocarbons, especially obtained in large quantities by the catalytic cracking, into an aircraft gasoline with a remarkably high octane number. In this connection it should be observed that this conversion can be effected by comparatively simple means.

What I claim is:

1. The process of making high-grade antiknock motor fuels which comprises treating the unsaturated hydrocarbons, derived from the cracking of high molecular hydrocarbons and having from about 3 to 5 carbon atoms in the molecule, to a selective polymerization of the unsaturated iso-hydrocarbons present, treating the resulting products with carbon monoxide and hydrogen at temperatures of at least about 300 C. under conditions producing the conversion of the alkenes present into alcohols, subjecting these alcohols to a dehydrating step under conditions producing the formation of alkenes and hydrogenating the resulting alkenes, thereby producing an aircraft fuel having a remarkably high octane number.

2. The process of claim 1 wherein the products obtained after the dehydrating step are separated into a high molecular fraction, a low molecular fraction and a medium fraction, the high molecular fraction being subjected directly to the hydrogenating step, the low molecular fraction being recycled to the selective polymerization step, and the medium fraction being recycled to the treatment with carbon monoxide and hydrogen.

3. The process of claim 1 wherein the reaction products are subjected to an isomerizing step after the dehydrating step and before hydrogenation.

4. The process of making high-grade antiknock motor fuels which comprises subjecting the unsaturated hydrocarbons, derived from the cracking of high molecular hydrocarbons and having from about 3 to 5 carbon atoms in the molecule, to the action of a catalyst selected from a class consisting of boryl phosphate and full'ers earth at a temperature ranging from about 200 to 300 0., treating the resulting products with carbon monoiride and hydrogen at a temperature of at least about 300 C. under conditions producing the conversion of the alkenes present into alcohols, subjecting these alcohols .to a dehydrating step, isomerizing the resulting product and then hydrogenating, thereby producing an aircraft fuel having a remarkably high octane num- "her.

'5. The process of making high-grade anti- -kno'ck fue1s which comprises treating the unsaturated hydrocarbons, having from 3 to 5 carbon atoms derived from the cracking of high molecular hydrocarbons, to isomerize them and to shift the double bonds towards the centers of the molecules "by contacting them with a catalyst :selected from a class-consisting of borylphosphate 4 and fullers earth at a temperature ranging from about 200 C. to 300 C. and then heating the resulting product with carbon monoxide and hydrogen under high pressures and at temperatures of at least about 300 C. under conditions producing the conversion of the alkenespresent into alcohols, subjecting these alcohols to;a dehydrat ing step under conditions producing the formation of alkenes and hydrogenating the resulting alkenes, thereby producing an aircraft fuel having a, remarkably high octane number.

'6.'The process of making high-grade antiknock fuels which comprises heating the unsaturated hydrocarbons, haVing from 3 to 5 carbon atoms derived "from the cracking of high molecular hydrocarbons to a selective polymerization of the unsaturated iso-hydrocarbons and then treating the resulting product with carbon monoxide andhyclrogen under high pressures and at temperatures of at leastabout 300 C. under conditions producing the conversion of the alk'enes present into alcohols, subjecting these alcohols to a dehydrating step under conditions producing the formation of alkenes and 'hydrogenating the resulting alkenes, thereby producing an aircraft fuel'having a remarkably high octane number.

AUGUST HAGEMANN. 

